Continuous passive motion applied to an injured or post operative leg is the primary rehabilitative treatment chosen by most doctors and therapists. Many leg and joint exercising devices are known. Generally, these machines have a motor driven leg support, with the leg support capable of being set to periodically move the leg in a preset range of positions, for a preset length of duration, and at a preset speed. Once these angles, speed, and duration have been chosen, the machine automatically moves the leg from a straightened position back and forth into these pre-chosen positions at the pre-chosen speed for the pre-chosen duration.
Resetting positions and safety cutoffs are available for the user of current machines. However, because all variables are preset and constant, typically, initial therapy cycles of the machine are often too severe and painful, whereas, later therapy cycles are insufficient due to the limbering of the joint and the joint's capability of greater movement as the therapy session progresses. Further, current machines do not allow for total knee joint isolation, but require hip joint movement in order to achieve knee movement.
Current machines and therapists do not sense the pain of the patient at all and do a limited job of sensing stiffness. A machine is needed that will allow total flexibility in the treatment of the leg, including flexion, extension, duration, and speed, but in doing so, the machine needs to be sensitive to the pain threshold of the patient and the flexibility of the joint being exercised.